Buckling-restrained diagonal brace using lapping and improved plugging connection

ABSTRACT

A buckling-restrained diagonal brace is provided. The buckling-restrained diagonal brace mainly contains a core element and a restraining element. The core element is an assembly of a specific number of steel members having a specific shape whose cross-sectional dimension is determined based on the load requirement. The core element has a larger cross-section at the ends than at its medial section. The core element is encased in the restraining element. The restraining element manly contains a single or multiple steel tubes filled with concrete, mortar, or reinforcing members. The restraining element is to protect the core element so that it wouldn&#39;t be buckled and destructed under load. By using a lapping or an improved plugging type of connection to a structure frame, the buckling-restrained diagonal brace is able to yield steadily when loaded in both tension and compression and the buckling-restrained diagonal brace would have a full hysteretic curve. The buckling-restrained diagonal brace has a significantly enhanced ductility and energy dissipation capability, and is able to reduce vibration and to lower seismic impact.

BACKGROUND OF THE INVENTION

(a) Technical Field of the Invention

The present invention generally relates to buckling-restrained diagonalbraces and, more particularly, to buckling-restrained diagonal bracesusing lapping and improved plugging types of connection.

(b) Description of the Prior Art

Conventional diagonal bracing members would suffer global and localbuckling when subjected to an axial force. The hysteretic curves ofthese conventional diagonal bracing members exhibit decreasing strengthand contracting behaviors. In addition, before their energy dissipationcapacity is fully utilized, conventional diagonal bracing members wouldbe broken due to excessively focused stress and strain. As such, formany years, seismic engineering researchers have been investigatingimprovements to the performance of diagonal braces, and variousbuckling-restrained diagonal braces are proposed to replace and enhanceconventional diagonal braces.

As shown in FIG. 1, buckling-restrained diagonal braces mainly contain acore element 11 and a restraining element 12. The axial force (tensionand compression) exerted on a diagonal brace is mainly taken by its coreelement 11. The restraining element 12, on the other hand, provideslateral strut so as to prevent the core element 11 from buckling underthe axial forces. If the core element 11 wouldn't buckle under axialforce, the axial strength and ductility of the core element 11 could beeffectively developed and the energy dissipation capacity of its steelmaterial could be fully utilized.

Accordingly, how to precisely control the core element 11's behaviorunder axial forces and how to increase the restraining effect havebecome the focus of studying and enhancing buckling-restrained diagonalbraces.

Conventional buckling-restrained diagonal braces usually use arectangular steel tube filled with concrete as the restraining element12, and the core element 11 usually has an “I” or “+” cross-sectionalshape. Because of the cross-sectional shape and the arrangement of theconnecting bolt holes at the end of the core element 11, the coreelement 11 relies on the use of a gusset plate 14, a joining plate 13,and bolts for butting connection with the structure frame. The joiningplate 13 also has a “+” shape. In addition, besides using the gussetplate 14 for connection, reinforcing plates have to be welded and boltholes have to be drilled to the two sides of the joining plate 13.

However, this kind of connection not only imposes a heavy weldingworkload, but also complicates and jams the connecting parts of thebuckling-restrained diagonal braces. In addition, in order to jointlytransfer axial force equally, the number of bolts required by usingjoining plate 13 is twice of that required by lapping connection.Therefore, the installation of conventional buckling-restrained diagonalbraces is very labor-intensive, time-consuming, operationallyinefficient, and is more difficult to control the quality.

On the other hand, as shown in FIG. 2, a plugging-typebuckling-restrained diagonal brace has been proposed to reduce thenumber of bolts and to avoid the use of joining plates. However, in thisconventional buckling-restrained diagonal braces, two parallel,equal-length, band-like steel bars spaced apart by a fixed distance areencased in a restraining element 22 of steel tube and concrete. When theconcrete is filled, it is difficult to position the two band-like steelbars in the restraining element 22 so as to maintain a precise spaceddistance. In addition, the installation of this plugging-typebuckling-restrained diagonal brace is directional sensitive. If the twoband-like steel plates are not well spaced, and the length of thediagonal brace is often greater than the beam width or column height ina single slant direction, the installation efficiency is inevitablydecreased and sometimes the installation is impossible.

SUMMARY OF THE INVENTION

Accordingly, to overcome the foregoing disadvantages and limitations ofconventional buckling-restrained diagonal braces, the present inventionprovides more efficient, economical, and convenient in installationseismic-proof, energy-dissipating diagonal braces.

The foregoing object and summary provide only a brief introduction tothe present invention. To fully appreciate these and other objects ofthe present invention as well as the invention itself, all of which willbecome apparent to those skilled in the art, the following detaileddescription of the invention and the claims should be read inconjunction with the accompanying drawings. Throughout the specificationand drawings identical reference numerals refer to identical or similarparts.

Many other advantages and features of the present invention will becomemanifest to those versed in the art upon making reference to thedetailed description and the accompanying sheets of drawings in which apreferred structural embodiment incorporating the principles of thepresent invention is shown by way of illustrative example.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevation diagram of a conventional buckling-restraineddiagonal brace having a “+” cross-section and using butting connection.

FIGS. 2A and 2B are a top view and a side view of a conventionalplugging-type buckling-restrained diagonal brace.

FIG. 3 is an elevation diagram of a conventional plugging-typebuckling-restrained diagonal brace.

FIG. 4 is an elevation diagram of a buckling-restrained diagonal braceusing lapping connection according the present invention.

FIG. 5A is a front view of the first embodiment of the presentinvention.

FIG. 5B is a top view of the first embodiment of the present invention.

FIG. 5C is a cross-sectional view along the A-A line of FIG. 5A.

FIG. 5D is a cross-sectional view along the B-B line of FIG. 5A.

FIG. 6A is a front view of the second embodiment of the presentinvention.

FIG. 6B is a top view of the second embodiment of the present invention.

FIG. 6C is a cross-sectional view along the A-A line of FIG. 6A.

FIG. 6D is a cross-sectional view along the B-B line of FIG. 6A.

FIG. 7A is a front view of the third embodiment of the presentinvention.

FIG. 7B is a top view of the third embodiment of the present invention.

FIG. 7C is a cross-sectional view along the A-A line of FIG. 7A.

FIG. 7D is a cross-sectional view along the B-B line of FIG. 7A.

FIG. 8 is an elevation diagram of a buckling-restrained diagonal braceusing improved plugging type of connection according to the presentinvention.

FIG. 9A is a front view of the fourth embodiment of the presentinvention.

FIG. 9B is a top view of the fourth embodiment of the present invention.

FIG. 9C is a cross-sectional view along the A-A line of FIG. 9A.

FIG. 9D is a cross-sectional view along the B-B line of FIG. 9A.

FIG. 10A is a front view of the fifth embodiment of the presentinvention.

FIG. 10B is a top view of the fifth embodiment of the present invention.

FIG. 10C is a cross-sectional view along the A-A line of FIG. 10A.

FIG. 10D is a cross-sectional view along the B-B line of FIG. 10A.

FIG. 11A is a front view of the sixth embodiment of the presentinvention.

FIG. 11B is a top view of the sixth embodiment of the present invention.

FIG. 11C is a cross-sectional view along the A-A line of FIG. 11A.

FIG. 11D is a cross-sectional view along the B-B line of FIG. 11A.

FIG. 12A is a front view of the seventh embodiment of the presentinvention.

FIG. 12B is a top view of the seventh embodiment of the presentinvention.

FIG. 12C is a cross-sectional view along the A-A line of FIG. 12A.

FIG. 12D is a cross-sectional view along the B-B line of FIG. 12A.

FIG. 13A is a front view of the eighth embodiment of the presentinvention.

FIG. 13B is a top view of the eighth embodiment of the presentinvention.

FIG. 13C is a cross-sectional view along the A-A line of FIG. 13A.

FIG. 13D is a cross-sectional view along the B-B line of FIG. 13A.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following descriptions are of exemplary embodiments only, and arenot intended to limit the scope, applicability or configuration of theinvention in any way. Rather, the following description provides aconvenient illustration for implementing exemplary embodiments of theinvention. Various changes to the described embodiments may be made inthe function and arrangement of the elements described without departingfrom the scope of the invention as set forth in the appended claims.

Besides improving the shortcomings of the conventionalbuckling-restrained diagonal braces, the present invention furtherprovides various enhanced and innovative installations, which conformmore closely to the requirements of seismic engineering and practicalapplication. Please refer to FIGS. 4 to 13. The major features of thepresent invention are described as follows.

An embodiment of the present invention is a buckling-restrained diagonalbrace using lapping connection. The present embodiment mainly contains apair of independently formed core members 311, 411, and a pair ofindependently formed restraining members 3211, 4211. The core elements31, 41 have members whose cross-sections are of “T,” “C,” “I,” or othershapes having single symmetry feature. The core members 311, 411 havelarger cross-sections at the ends than at their medial sections. Thecore members 311, 411 are encased in the restraining members 3211, 4211of the restraining elements 32, 42. During fabrication, two assembliesof core and restraining members are manufactured separately. At theconstruction site, the two assemblies of core and restraining membersare lapped to the structure frame. In other words, each of the twoassemblies of core and restraining members are lifted at the two sidesof separating plates 34, 46, and lapped to the separating plates 34, 46with bolts. Then, bonding plates 322, 422 are welded to bond the tworestraining members 3211, 4211 and complete the installation. As such,there is no problem of difficult positioning and installation. Therestraining elements 32, 42 could be lateral support members made ofpure steel, or the restring elements 32, 42 could use common restrainingmembers of steel tubes filled with concrete or mortar. The restrainingelements 32, 42 prevent the core elements from buckling when undercompression.

In another embodiment, the restraining members 3211, 4211 of therestraining elements 32, 42 could also use pure steel or a single steeltube filled with concrete or mortar. Their ends are fixedly locked byend plates 43, in order to match the variations in cross-section andconstruction of the core elements and restraining element 32, 42. On theother hand, to facilitate their connection and construction, the presentembodiment improves the conventional plugging type of connection.Independent plugging connection pate 34, 44 having end plates 43 arefirst fixedly locked to the joining plates 34, 46 of the structureframe. Then, the end plate 43 is closely attached to an end plate of thediagonal brace and bolted together to complete the installation at oneside. The installation at the other side is completed identically. Thistype of buckling-restrained diagonal braces, due to the reduceddimension of its media section's cross-section and hence concentratingthe energy dissipation at the media section, conforms more closely tothe functional requirements of diagonal braces. On the other hand, usingjoining plates 34, 46 for locking, the restraining elements 32, 42 andcore elements 31, 41 could have their cross-sections flexibly chosenbased on the requirements of designed strength and material used,without subjecting to the limitations of conventional connection. This,therefore, has significantly increased the applicability andconfiguration of cross-sections.

In summary, buckling-restrained diagonal braces using lapping orimproved plugging types of connection not only retain the superiormechanics characteristics of conventional buckling-restrained diagonalbrace, but also have benefits such as easy installation, simple joiningstructure, and better manufacturing quality control, etc.

It will be understood that each of the elements described above, or twoor more together may also find a useful application in other types ofmethods differing from the type described above.

While certain novel features of this invention have been shown anddescribed and are pointed out in the annexed claim, it is not intendedto be limited to the details above, since it will be understood thatvarious omissions, modifications, substitutions and changes in the formsand details of the device illustrated and in its operation can be madeby those skilled in the art without departing in any way from the spiritof the present invention.

1. Buckling-restrained diagonal braces using lapping and improvedplugging types of connection, comprising a core element and arestraining element, said core element being an assembly of steelmembers having an arbitrary and symmetrical cross-sectional shape, saidcore element having a larger cross-section at its end than at its medialsection, said core element encased in said restraining element, saidrestraining element being a casing assembled by at least one steel tubemember filled with one of concrete, mortar, and reinforcing members,said core element restrained by said restraining element so that saidcore element would not be buckled and destructed under compression andsaid buckling-restrained diagonal brace would steadily yield and has afull hysteretic curve so as to increase significantly its energydissipation capability, to reduce vibration, and to lower seismicimpact.
 2. The buckling-restrained diagonal brace using lappingconnection according to claim 1, characterized in comprising: a pair ofindependently formed restraining members; a pair of independently formedcore members, each of said core members having a bar shape and a largercross-section at said core member's ends than that of said core member'smedia section, each of said core members encased in one of saidrestraining members respectively, said core members connected to astructure frame using lapping type of connection; and a bonding platefor bonding said restraining members.
 1. The buckling-restraineddiagonal brace using lapping connection according to claim 2, whereineach of said pair of restraining members is a steel tube filled with amaterial selected from the group consisting of concrete and mortar. 2.The buckling-restrained diagonal brace using lapping connectionaccording to claim 2, wherein said pair of restraining members are madeof pure steel and comprise a steel tube, and steel plate and bolts forconnecting said steel tube.
 3. The buckling-restrained diagonal braceusing improved plugging type of connection according to claim 1,characterized in comprising: a restraining member having at least onesteel tube; a symmetrical core member, said core member having a largercross-section at said core member's ends than that of said core member'smedial section, said core member fixedly locked by end plates at saidcore member's ends; and plugging connection plates for connecting saidbuckling-restrained diagonal brace and a structure frame.
 4. Thebuckling-restrained diagonal brace using improved plugging type ofconnection according to claim 5, wherein each of said pair ofrestraining members is a steel tube filled with a material selected fromthe group consisting of concrete and mortar.
 5. The buckling-restraineddiagonal brace using improved plugging type of connection according toclaim 5, wherein each of said pair of restraining members is made ofpure steel, and comprises a steel tube, and steel plate and bolts forconnecting said steel tube.
 6. The buckling-restrained diagonal braceusing improved plugging type of connection according to claim 5, whereinsaid core element and said restraining element have arbitrary shapes andcross-sections, and are assemblies of an arbitrary number of members. 7.The buckling-restrained diagonal braces using lapping and improvedplugging types of connection according to claim 1, wherein said coreelement is characterized in that said core element is an assembly with aplurality of sections that have different cross-sections respectivelyand that a medial section has a material strength no greater than thatof end sections.
 8. The buckling-restrained diagonal braces usinglapping and using improved plugging types of connection according toclaim 1, wherein said restraining element is characterized in thatconstituent members of said restraining element are made of a materialselected from the group consisting of metallic materials, non-metallicmaterials, and combinations of metallic and non-metallic materials.